JP2002166916A - Biaxial drawing blow-molded light-weighted bottle container made of synthetic resin and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bottle container having a large buckling strength while an amount of a used synthetic resin material is reduced, and a manufacturing method thereof. SOLUTION: The biaxial drawing blow-molded light-weighted bottle container made of a synthetic resin has a wall, containing at least one cross section where a point of inflection at a joint between parts having different cross-sectional areas mainly on a cylindrical wall passes through, with a thickness of 109% or more for an average thickness of drawing-blown parts. The bottle container has joints between heels 14, 24 and 34 and bottoms 15, 25 and 35, waists 16 and 26, dented ribs 27, 37 and 39, and a protrusion 28 formed thick.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially stretch blow molded lightweight bottle made of synthetic resin and a method for producing the same.

[0002]

2. Description of the Related Art At present, synthetic resin bottles are widely used in beverage containers and many other fields. However, effective use of resources, reduction of manufacturing costs, reduction of waste when disposing of bottles, etc. In order to achieve this, the amount of synthetic resin material used is reduced by reducing the thickness of the synthetic resin bottle container.

[0003]

However, when a container having a reduced thickness and filled with a content liquid is stacked on a pallet or the like, the weight of the bottle to be stacked (including the content liquid) is required. Hangs on the container located below,
Even after stacking, the weight of the stacked bottles (including the liquid content) located above will fall on the containers located below. That is, the container located below is subjected to a force in the container axial direction from above, but in this case, the stress is concentrated at the inflection point. For example, in the case of a bottle having a substantially rectangular cross section having a waist portion 46 whose diameter is reduced at the center of the trunk as shown in FIG.
4,465,466,467, and the heel portion 44
Have inflection points 443, 444, and 445 between the bottom and the bottom 45. When an axial force is applied from above, the pressing force from above causes an inflection point along the circumferential direction at these inflection points. A component force directed radially outward also acts, causing buckling deformation, and in some cases, there has been a problem that the waist portion, the bottom portion, and the periphery thereof are crushed.

[0004]

In order to prevent the buckling deformation and crushing of the bottle, the present invention reduces the amount of synthetic resin material used while reducing the wall containing these inflection points. We decided to give strength by making it thick,
Accordingly, a method of manufacturing a bottle container having a large buckling strength is provided, and the buckling strength at the inflection point is increased.

According to the first aspect of the present invention, there is provided a biaxially stretch blow molded lightweight bottle made of synthetic resin, wherein an inflection point mainly passes through a connecting portion between portions having different cross-sectional areas of a cylindrical wall. A biaxially stretch blow molded lightweight bottle container made of synthetic resin, characterized in that a wall including at least one cross section has a thickness of at least 109% of the average thickness of the stretch blown portion. Can be At least one through which the inflection point passes
The wall thickness changes gradually from the wall including one cross section to the wall of the other portion that has been stretch blown (claim 2). According to the invention described in claim 3, the lightweight bottle container is constituted by a mouth portion, a shoulder portion, a trunk portion, a heel portion, and a bottom portion, and is provided between portions having different cross-sectional areas of the cylindrical wall. A lightweight bottle container is provided wherein the connection is a connection between the heel and the bottom tread. Preferably, the thickness of the entire bottom contact surface is at least 109% of the average thickness. Further, a lightweight bottle container is provided in which a connecting portion between portions having different cross-sectional areas of the cylindrical wall is a connecting portion between the shoulder portion and the body portion (claim 5). Further, a waist portion is formed on the body portion, and the body portion includes an upper half body portion located at an upper portion of the waist portion and a lower half body portion located at a lower portion of the waist portion, and A light-weight bottle, wherein the connecting portions between portions having different cross-sectional areas of the wall are a connecting portion between the upper half body and the waist portion and a connecting portion between the lower half body and the waist portion. A body container is provided (claim 6).

According to the present invention, there is provided a method for producing a biaxially stretched blow-molded lightweight bottle container by heating a preform and subjecting the preform to biaxially stretch blow molding. During the heating, the part of the preform corresponding to at least one inflection point mainly at the connection between the parts having different cross-sectional areas of the cylindrical wall is compared with the parts of the other preform to be stretch blow-molded. The thickness of the wall including the cross section through which the inflection point passes when the biaxial stretch blow molding is performed by reducing the degree of heating and thereby the degree of stretching of the portion having a small degree of heating is stretch blow molded. A method is provided for making a biaxially stretch blow molded lightweight bottle container characterized by being at least 109% thicker than the other parts. Preferably, the preform is heated, and the preform is subjected to primary biaxial stretching blow molding using a primary blow mold to form a primary intermediate molded product, and the primary intermediate molded product is heated and forcedly heated. To form a secondary intermediate molded product, and the secondary intermediate molded product is subjected to secondary biaxial stretching blow molding to form a biaxially stretched blow molded lightweight bottle container (claim 8).

[0007]

1 to 3 show a bottle container according to a first embodiment of the present invention. Bottle container 1 shown in FIGS.
Is a lip 11, a shoulder 12 extending downward from the lower end of the lip, a trunk 13 hanging down from the lower end of the shoulder, and a heel extending downward from the lower end of the trunk 13 in the axial direction of the bottle container. And a bottom portion 15 forming a bottle container grounding surface. The body 13 has a substantially quadrangular (octagonal shape by chamfering) cross section, and includes a wide panel portion 131 and a narrow diagonal column portion 132 disposed between the panel portions (FIG. 2, 3). In addition, the trunk 13 is a waist 1 described later.
6, the upper half body part 133 and the lower half body part 134 are divided, the panel 131 part is divided into an upper panel part 135 and a lower panel part 136, and the diagonal column part 132 is divided into an upper diagonal column part. 137 and a lower diagonal column 138. Each of the upper panel portion 135 and the lower panel portion 136 is formed with a panel 139 for absorbing the reduced pressure in the bottle.

A waist portion 16 having a reduced diameter and recessed inward is formed at a substantially central portion in the axial direction of the body portion 13. The waist portion 16 includes an upper wall 161 extending inward below the lower ends of the upper panel portion 135 and the upper diagonal column portion 137, a vertical wall 162 hanging down from a lower end of the upper wall 161, and an outer side of the lower end of the vertical wall 162. A lower wall 163 extends downward and is connected to the upper end of the lower panel 136 and the lower diagonal column 138. The cross-sectional area of the waist portion 16 in the vertical wall 162 is smaller than the cross-sectional area of the upper half body portion 133 and the lower half body portion 134.

In the waist portion 16, when a force is applied in the axial direction from above the bottle container, buckling deformation is likely to occur. In the waist portion 16, an inflection point 164 is formed between the upper half body portion 133 and the upper wall 161.
An inflection point 165 between the vertical wall 162 and the vertical wall 162, and an inflection point 166 between the vertical wall 162 and the lower wall 163.
An inflection point 167 is provided between the lower wall 163 and the lower half body portion 134. That is, in the present invention, the inflection point means an inflection point appearing in a longitudinal section of the bottle container, which is caused by a change in the cross-sectional area of the bottle container. When a force is applied in the axial direction from above the bottle container, the forces acting at these inflection points generate a component force in the axial direction and in the direction perpendicular to the axis, so that buckling deformation is likely to occur. It is. Therefore, the upper half body part 133 with a large cross-sectional area,
The wall thickness at the inflection points 164, 165, 166, and 167 in the continuous portion of the vertical wall 162 of the waist portion 16 having the small cross-sectional area and the lower half body portion 134 having the large cross-sectional area is increased by the thickness of the other portions to be stretch blown. If it is formed thicker than the average thickness, the buckling strength at the waist portion 16 can be increased.

According to the present inventors, the thickness of the side wall of the bottle is
It has been experimentally confirmed that the strength of the bottle becomes extremely strong when the thickness is at least 109% of the average thickness of the stretch blown portion. Therefore, the inflection points 164, 165, 1
The wall at 66,167 was at least 109% thicker than the average thickness of the stretch blown portion. If it is less than 109%, sufficient strength cannot be obtained. Although there is no particular upper limit for the wall thickness, it is preferably up to 250% in consideration of an increase in the amount of resin used, a reduction in the degree of stretching, and whitening.

The bottle container of the present invention is manufactured by biaxial stretch blow molding. Therefore, when the inflection point is made thicker, the thickness does not differ stepwise, and the thickness changes gradually around the inflection point. For example, at the inflection point 164, The wall thickness does not change stepwise from the upper body 133 to the inflection point 164, but changes gradually as shown in FIG. FIG.
In the cross section of FIG. 4 (and FIGS. 4 and 6), the thickness is exaggerated.

Adjacent inflection points (eg, 164 and 165)
Are close to each other, and since the change in the thickness is gentle as described above, the thickness between the inflection points is substantially equal to the thickness at the inflection point. Therefore, the thickness of the bottle container is, as shown in FIG.
The thickness becomes more gentle, and the thickness at the inflection point 164 becomes 109% or more.
To the wall thickness (wall thickness 109%), inflection point 1
The thickness gradually decreases from 67 to the lower half body part 134.

The heel portion 14 is continuous from the lower half body portion 134, and the cross-sectional area of the heel portion 14 is
Equal to or less than the cross-sectional area at 34. The bottom 15 has a grounding wall 151 and forms the bottom grounding surface of the bottle container. The cross-sectional area of the bottom portion 15 (indicated by the dashed line in FIG. 3) is smaller than the cross-sectional area of the heel portion 14. Between the heel portion 14 and the bottom portion 15, a connecting portion from the heel portion 14 to the bottom portion 15 has a curved surface whose diameter decreases as going downward, and at a position where the bottom portion 15 starts to bend toward the heel portion 14. Inflection point 14
3, and has an inflection point 144 at a point where the heel portion 14 starts to bend toward the grounding wall 141.
At an inflection point 145 at a substantially intermediate point between
have.

In the heel portion 14 and the bottom portion 15 as well, when a force is applied in the axial direction from above the bottle container, buckling deformation is likely to occur at the inflection points 143, 144 and 145.
This is because the force from the upper side of the bottle applied to the heel portion 14 which is a vertical wall, at the inflection points 143, 144 and 145,
To produce a component force in the axial direction and in the direction perpendicular to the axis,
It seems that buckling deformation is likely to occur. Therefore, in order to increase the buckling strength of the heel portion 14 and the bottom portion 15, portions where a component force is likely to occur, that is, inflection points 143, 144, 1
The wall including 45 (around the ground contact wall) may be formed to be at least 109% thicker than the average thickness of the stretch blown portion.

In the present invention, the inflection points 143, 144, 14 located at the connection between the heel portion 14 and the bottom portion 15 are provided.
Not only 5 but also the entire grounding wall 151 of the bottom 15 (that is, the entire bottom grounding surface) may be thick. Thereby, the whole bottom part 15 can be strengthened.

In addition, in the bottle container 1 shown in FIGS. 1 to 3, the shoulder 12 and the upper half body 133 are defined as "the inflection point at the connection between the sections having different cross-sectional areas of the cylindrical wall". And an inflection point 122 slightly below the axial center of the shoulder portion 12, and these inflection points may be made thicker. However, the bottle container 1 having the structure shown in FIGS.
, The external force from above can be absorbed mainly by the elastic deformation of the waist portion 16 and the vicinity of the bottom portion 15. Therefore, in the bottle container 1 having the structure shown in FIGS. The wall pressure at 121 and 122 need not be thick. In the present invention, it is determined whether or not to be thick in view of the specific structure and strength of the bottle container.

The pressing force from above acts on the inflection point formed over the entire circumferential direction as a component force directed in the direction perpendicular to the axial direction. In other words, the axial direction of the bottle container is defined as the axis. Mainly acts on the inflection point in the concavo-convex portion formed in a cylindrical shape. Particularly, in the bottle container 1 shown in FIGS. The inflection point existing on the periphery of the panel 139 that is not formed over the entire surface is hardly applied. Therefore, the peripheral edge of panel 139 does not need to be thick. Note that the cylindrical wall does not necessarily mean that the cross section is circular, but may be a rectangular wall or other polygonal cross section like the bottle container shown in FIGS. Including.

FIGS. 4 and 5 show a second embodiment of the present invention. The bottle container 2 shown in FIGS.
It comprises a shoulder 22, a trunk 23, a heel 24, and a bottom 25. The bottle container 2 shown in FIGS.
Has a substantially circular cross-sectional shape unlike the bottle container shown in FIG.
7 are formed, and a protruding portion 28 is formed continuously below the waist portion 26. A waist portion 26 and a protruding portion 28 are formed at a substantially central portion in the axial direction of the trunk portion 23. The trunk portion 23 is divided into an upper half trunk portion 233 and a lower half trunk portion 234, and the lower half trunk portion 234 is formed. Is formed with a panel 239 for absorbing the reduced pressure in the bottle.

The waist portion 26 has an upper wall 261 extending inward below the lower end of the upper half body portion 233, a vertical wall 262 hanging down from the lower end of the upper wall 261, and extending outward and downward from the lower end of the vertical wall 262. It comprises a lower wall 263 connected to the upper end of the protrusion 28. The protrusion 28 is provided at the waist 26
A vertical wall 281 that hangs down from the lower end of the lower wall 263, and extends inward below the lower end of the vertical wall 281.
And a lower wall 282 continuous with the lower wall 282. The waist 26 and the protrusion 28 are located at inflection points 264, 265, 266, 26
7,283,284. In the second embodiment, these inflection points 264, 265, 266, 267, 2
The wall of the cross section passing through 83,284 is formed to be 109% or more of the average thickness of the stretch blow-molded portion. Since the adjacent inflection points are close to each other, the thickness is substantially equal from the inflection point 264 to the inflection point 284 as in the first embodiment.

The bottle container 2 shown in FIGS. 4 and 5 has inflection points 243, 244 and 245 at the connection between the heel portion 24 and the bottom portion 25, as in the first embodiment. The wall of the cross section passing through the inflection point is formed to have a thickness of 109% or more with respect to the average thickness of the stretch blow-molded portion. The thickness is substantially the same from the inflection point 243 to the inflection point 245 as in the first embodiment. Also, as in the first embodiment,
The entire ground wall 251 of the bottom 25 (ie, the entire bottom ground plane)
Is 109% of the average thickness of the stretch blow molded part.
% Or more to enhance the entire contact surface.

Unlike the first embodiment, the bottle container 2 has a concave rib 27 between the lower end of the body 23 and the heel 24.
Are formed. The concave rib 27 has a diameter reduced with respect to the lower half body portion 234 and the heel portion 24,
272, 273, and 274, and a wall having a cross section passing through these inflection points is formed to be 109% or more of the average thickness of the stretch blow-molded portion. From the inflection point 271 to the inflection point 274, the thickness is substantially equal. With the above configuration, the waist portion 26, the concave rib 27, and the heel portion 2 of the bottle container 2
The portion extending from 4 to the bottom 25 is reinforced, and a bottle container with high buckling strength is obtained. Except for the above, the second embodiment is the same as the above-described first embodiment, and a description thereof will be omitted.

FIGS. 6 and 7 show a third embodiment of the present invention. The bottle container 3 shown in FIGS. 6 and 7 includes a mouth portion 31, a shoulder portion 32, a body portion 33, a heel portion 34, and a bottom portion 35, and has a substantially circular cross section. A panel 339 is formed on the body portion 33 and extends in the axial direction from the vicinity of the upper end of the body portion to the vicinity of the lower end of the body portion. In the bottle 3 of the third embodiment, the body 33
No waist portion is formed. As in the first and second embodiments, the bottle container 3 has inflection points 343, 344, at the connection between the heel portion 34 and the bottom portion 35.
345. Further, in the bottle container 3, similarly to the bottle 2 of the second embodiment, a concave rib 37 is formed between the body portion 33 and the heel portion 34, and the inflection points 371, 372,
373 and 374. The wall of the cross section passing through these inflection points is 10% of the average wall thickness of the stretch blow molded part.
9% or more is formed.

Further, the bottle container 3 includes a shoulder portion 32 and a body portion 33.
A concave rib 39 is also formed between them. Concave rib 39
Has inflection points 391, 392, 393, and 394, and the wall of the cross section passing through these inflection points is formed to be 109% or more of the average thickness of the stretch blow-molded portion.
The wall thicknesses are substantially equal from the inflection points 343 to 345, from the inflection points 371 to 374, and from the inflection points 391 to 394, as in the first embodiment and the second embodiment. Except for the above, the third embodiment is the same as the above-described first and second embodiments, and a description thereof will be omitted.

Each container in the first to third embodiments includes:
The preform made of polyethylene terephthalate resin is made by biaxial stretching blow molding. However, the present invention is not limited to the container made of polyethylene terephthalate, but can be applied to other synthetic resins.

In order to locally increase the wall thickness only at the inflection point, it is sufficient that the degree of heating of the preform in the portion formed at the inflection point in the final bottle container is smaller than that in the other portions. Thereby, the stretching degree becomes small in the portion where the degree of heating is small, so that the part can be made thick.

Other than the above-described method of heating the preform, a conventional synthetic resin bottle container manufacturing method can be used, including ordinary biaxial stretch blow molding and the following two-step method. It can be formed by biaxial stretch blow molding.

FIG. 1 shows a two-stage stretch blow molding.
Embodiments for manufacturing the containers shown in FIGS. 1 to 3 will be described with reference to FIGS. First, a cylindrical preform P with a bottom made of polyethylene terephthalate is prepared.

The preform is heated to 70 to 130 ° C., more preferably 90 to 120 ° C., at which the stretching effect can be exhibited. In the illustrated embodiment, portions to be heated by a heater (not shown) are divided into sections, and the degree of heating of the preform in each section is made different, so that a portion corresponding to a portion to be made thick in the bottle container is formed. Reduce the degree of heating.

The preform thus heated is subjected to primary biaxial stretching blow molding to form a primary intermediate molded product.
The temperature of the primary mold used for primary biaxial stretch blow molding is 50
To 230 ° C, more preferably 70 to 180 ° C. The stretching area ratio from the preform to the primary intermediate molded product is 4 to 22 times, preferably 6 to 15 times, based on the preform, and is sufficiently stretched to increase the resin density, thereby reducing the heat resistance of the bottle container. I will increase it. The primary intermediate molded product is formed larger than the bottle container to be finally formed. A portion to be thick in the bottle container (in the bottle container of FIG. 1, the waist portion 16 from the inflection point 164 to the inflection point 167,
And the wall corresponding to the portion between the inflection point 143 and the inflection point 145) is formed thick in the primary intermediate molded product.

The thus obtained primary intermediate molded article is subjected to a heat treatment and heat shrinkage to obtain a secondary intermediate molded article. The temperature immediately after the heating is 110 to 255 ° C, preferably 130 to 200 ° C. By this heating, the primary intermediate molded product is forcibly shrunk, and the residual stress generated in the primary intermediate molded product in the primary biaxial stretch blow molding is released. In this heat treatment step, the primary intermediate molded product undergoes heat shrinkage, but since the portion corresponding to the thickened portion in the bottle container is made thicker in the primary intermediate molded product, it corresponds to the secondary intermediate molded product. The portion is still thicker than the other stretched portions.

The secondary intermediate molded article is subjected to secondary biaxial stretching blow molding to obtain a final bottle container. The temperature of the secondary mold used for the secondary biaxial stretch blow molding is 60 to 170 ° C, preferably 80 to 150 ° C. The draw ratio from the secondary intermediate product to the final bottle container is smaller than the draw ratio from the preform to the primary intermediate product. Therefore, the residual stress generated by the secondary biaxial stretch blow molding is smaller than the residual stress generated by the primary biaxial stretch blow molding. The bottle container thus obtained has a high heat resistance having a resin density of 1.380 to 1.395 g / cm3. In addition, in the bottle container of FIG. The waist portion 16 and the portion from the inflection point 143 to the inflection point 145 have a thickness of at least 109% of the average thickness of the stretch blown portion, and have high buckling strength. is there.

In the above-described embodiment, the thickness of the preform is changed by changing the degree of heating of the preform. Alternatively, the thickness of the portion corresponding to the thick portion in the bottle container may be changed. A reform may be formed into a thick wall and formed into a bottle container by ordinary blow molding, or may be formed by using both the change in the degree of heating of the preform and the adjustment of the thickness of the preform. It is also possible.

[0033]

EXAMPLE A preform made of polyethylene terephthalate was prepared to produce the biaxially stretch blow-molded lightweight bottle container shown in FIG. The preform was heated. In this case, the preform heating part by the heater was sectioned. In FIG. 8, the preform is divided into seven sections, and a first section, a second section to a seventh section from the lip portion,
The third section, which is the portion corresponding to the waist portion 16 of the final bottle container, is reduced by 25% (that is, the output is 75%) to the average of the entire heater output, and the portion corresponding to the center of the bottom inside from the inflection point 143. 17% reduction in 6th section (ie 83% output)
And As described above, the preform is 90-120
Heated to within ° C.

The preform heated in this way is
Primary biaxial stretch blow molding was performed using a primary mold heated to 0 ° C. to obtain a primary intermediate product. This primary intermediate was heated to 160 ° C. and shrunk to obtain a secondary intermediate. This secondary intermediate,
Using a secondary mold heated to 95 ° C., secondary stretch blow molding was performed to obtain a final bottle having an internal volume of 500 ml. When the thickness of the obtained bottle container was measured, the average thickness of the stretch-blown portion was 0.330 mm, and the thickness of the waist portion 16 was 0.359 m.
m (ie, 109%), and the thickness of the connecting portion between the heel portion 14 and the bottom portion 15 was 0.363 mm (ie, 110%). The buckling strength of the bottle container was 324N. In this embodiment,
The waist 16 has a thickness of 109% and the connection between the heel 14 and the bottom 15 has a thickness of 110%, based on the average thickness of the stretch blown portion. However, the present invention is not limited to these numerical values, depending on the difference in the mechanical structure of the bottle container, such as the presence or absence of ribs.

[0035]

Comparative Example For comparison, a bottle container was manufactured using the same method as in the above example, except that the output of the heater in the third section and the sixth section was not reduced with respect to heating of the preform. did. The wall thickness of the obtained bottle container is
105% at the waist 16 and 107% at the connection between the heel and the bottom, based on the average thickness of the stretch blown part
And the buckling strength of the bottle container was about 255N.
The difference in the buckling strength between the example and the comparative example is larger than the difference in the thickness between the example and the comparative example, but this is because the buckling strength is approximately the square of the thickness. This is because it is considered to be proportional.

[0036]

According to the first aspect of the present invention, the wall including at least one cross section through which the inflection point passes at the connecting portion between the portions having different cross-sectional areas of the cylindrical wall is mainly used for the stretch blown portion. Since the thickness is 109% or more of the average thickness, the buckling strength increases, and buckling deformation occurs at these inflection points even if a component force occurs in the direction perpendicular to the bottle container axis direction. Since the other portions stretch-blown are not formed, and the other portions are formed to be thin, it is possible to reduce the amount of the synthetic resin material used.

According to the third aspect of the present invention, the wall including the inflection point (that is, the peripheral portion of the grounding wall) in the connection portion between the heel portion and the grounding wall is 109% of the average thickness of the stretch blown portion.
% Or more, the buckling strength around the ground contact wall is increased. According to the invention of claim 4, the thickness of the entire grounding wall is set at 10 times the average thickness of the stretch blown portion.
Since the thickness is 9% or more, the buckling strength of the entire contact wall is increased. According to the fifth aspect of the present invention, the wall including the inflection point at the connecting portion between the shoulder portion and the body portion (that is, the peripheral portion of the grounding wall) is 109% smaller than the average thickness of the stretch blown portion.
% Or more, the buckling strength of the connecting portion between the shoulder and the trunk increases. According to the invention of claim 6, the wall including the inflection point (that is, the waist portion) in the connecting portion between the upper half body portion and the waist portion and the connecting portion between the lower half body portion and the waist portion are formed. Since the thickness is 109% or more of the average thickness of the stretch blown portion, the buckling strength of the waist portion is increased.

According to the invention of claim 7, by changing the degree of heating of the preform, the bottle container having a large buckling strength specified in claims 1 to 5 can be easily obtained. Since the steps other than the heating step are the same as in the prior art, the bottle containers of claims 1 to 5 can be easily obtained. According to the invention of claim 8, two-stage biaxial stretch blow molding is used, and the internal residual stress in the primary biaxial stretch blow molding is released by heat treatment, so that a bottle container having high heat resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially sectional front view of a bottle container according to a first embodiment of the present invention.

FIG. 2 is a plan view of the bottle container shown in FIG.

FIG. 3 is a bottom view of the bottle container shown in FIG. 1;

FIG. 4 is a partial cross-sectional front view of a bottle container according to a second embodiment of the present invention.

FIG. 5 is a plan view of the bottle container shown in FIG.

FIG. 6 is a partially sectional front view of a bottle container according to a third embodiment of the present invention.

7 is a plan view of the bottle container shown in FIG.

FIG. 8 is a partial cross-sectional front view showing a preform heating method according to the present invention.

FIG. 9 is a front view, partially in section, of a bottle container according to the prior art.

[Explanation of symbols]

11, 21, 31 Mouth, 12, 22, 32 Shoulder, 13, 23, 33 Body, 14, 24, 34 Bottom, 16, 26 Waist, 27, 37, 39 Concave rib, 28 Projection, 143 , 144, 145, 243, 244, 245, 3
43,344,345 inflection points, 164,165,166,167,264,265,2
66,267 inflection point, 271,273,273,274,371,372,3
73,374 inflection point, 283,284 inflection point, 391,392,393,394 inflection point

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoki Tsutsui 3-2-6 Oshima, Koto-ku, Tokyo Inside Yoshino Kogyo Co., Ltd. (72) Inventor Naoto Hara 3-2-6 Oshima, Koto-ku, Tokyo Yoshino Kogyo Co., Ltd. In-house (72) Inventor Tomoyuki Ozawa 3-2-6 Oshima, Koto-ku, Tokyo Inside Yoshino Kogyo Co., Ltd. Hiromi Yaguchi 21-3 Matsuyamacho, Moka-shi, Tochigi F-term in Moka factory of Yoshino Works, Ltd. (reference) 3E033 AA01 AA02 BA18 CA02 CA05 DA03 DB01 DC10 DD05 EA03 EA04 EA05 EA06 EA12 FA03 4F208 AG07 AG22 AG23 AH55 LA02 LA04 LB01 L03 LA03 LH07 LN29

Claims (8)

[Claims] 1. A biaxially stretch blow molded lightweight bottle container made of synthetic resin, comprising a wall including at least one cross section through which an inflection point passes mainly at a junction between portions having different cross-sectional areas of a cylindrical wall. A biaxially stretch blow molded lightweight bottle container made of synthetic resin, characterized in that the thickness is 109% or more of the average thickness of the stretch blown portion. 2. The synthetic resin according to claim 1, wherein the wall thickness changes gradually from a wall including at least one cross section through which the inflection point passes to a wall of another stretch blown portion. Biaxial stretch blow molded lightweight bottle container. 3. The bottle container includes a mouth portion, a shoulder portion, a body portion, a heel portion, and a bottom portion, and a connecting portion between portions having different cross-sectional areas of the cylindrical wall includes a heel portion. The lightweight biaxially stretch blow-molded bottle container made of synthetic resin according to claim 1 or 2, which is a connection portion with the bottom contact surface. 4. The lightweight biaxially stretch blow molded bottle made of synthetic resin according to claim 3, wherein the thickness of the entire bottom contact surface is at least 109% of the average thickness. 5. A connecting portion between portions of the cylindrical wall having different cross-sectional areas is a connecting portion between the shoulder and the body.
The lightweight biaxially stretch blow molded bottle container according to claim 3. 6. A waist portion is formed on the trunk portion, wherein the trunk portion is located on an upper half of the waist portion,
A lower half body portion located at a lower part of the waist portion; a connecting portion between portions having different cross-sectional areas of the cylindrical wall; a connecting portion between the upper half body portion and the waist portion; The synthetic resin biaxially stretch blow-molded lightweight bottle container according to claim 3, which is a connecting portion between the half body portion and the waist portion. 7. A method for manufacturing a biaxially stretch blow-molded lightweight bottle container by heating a preform and subjecting the preform to biaxial stretch blow molding, wherein the preform is heated mainly by traversing a cylindrical wall. A portion of the preform corresponding to at least one inflection point in a connection between portions having different areas is reduced in the degree of heating as compared with the portions of the other preform to be stretch blow-molded, thereby reducing the degree of heating. The degree of stretching of the small portion is reduced so that the wall thickness including the cross section through which the inflection point passes when biaxially stretch blow-molded is at least 109% thicker than that of the other stretch-blown portion. A method for producing a biaxially stretch blow-molded lightweight bottle container. 8. A preform is heated, and the preform is subjected to primary biaxial stretching blow molding using a primary blow mold, thereby forming a primary intermediate molded product, and heating the primary intermediate molded product. Forcibly shrinking to form a secondary intermediate molded product, and forming the secondary intermediate molded product in a secondary biaxial stretch blow molding to form a biaxially stretch blow molded lightweight bottle container. The method of claim 7.